Hello,
On Thu, Oct 19, 2006 at 03:22:02AM -0500, Andy Howell wrote:
> Hello,
>
> I'm tying to understand how defines get added to config.h. In my
> configure.ac file I have:
>
> if test "apple" = "orange"; then
> AC_DEFINE_UNQUOTED(HAVE_SOMETHING,1,[Define if SOMETHING])
> fi
>
> My test fails, so I don't expect to get
>
> /* Define is SOMETHING */
> #define HAVE_SOMETHING 1
>
> in config.h
>
> I did a sh -x on configure, but I never see it do HAVE_SOMETHING.
it is OK.
The template config.h.in contains `#undef HAVE_SOMETHING'.
(It is usually created by autoheader.)
Configure collects all AC_DEFINES, the one you quoted above is not
executed, of course.
At the end, configure creates and calls config.status.
config.status makes substitutions for all AC_DEFINES, but
HAVE_SOMETHING is not among them, so the `#undef HAVE_SOMETHING'
stays there. Then it comments out all #undefs, but that's a general
substitution, ie. it does not contain `HAVE_SOMETHING'.
Hope this helps,
Stepan Kasal
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